Gas operated percussion drilling tool



Nov. 19, 1963 Filed April 17, 1961 L. B. WILDER GAS OPERATED PERCUSSIONDRILLING TOOL h *5 6 I E l8 -IT 2 Sheets-Sheet l FIG.2

LAWRENCE B. WILDER IN V EN TOR.

- BY Zawfl 14 ATTORNEY Nov. 19, 1963' 1.. B. WILDER 1 GAS OPERATEDPERCUSSION DRILLING TOOL 7 Filed April 17, 1961 2 Sheets-Sheet 2 47 ll47 HI i 34 4 48 I .4 .A

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FIG. 4

LAWRENCE B.W|LDER INVENTOR.

ATTORNEY United States Patent 3,111,176 GAS OPERATED PERCUSSION DRILLINGTOUL Lawrence B. Wilder, Tulsa, Okla, assignor to Pan American PetroleumCorporation, Tulsa, Okla, a corporation of Delaware Filed Apr. 17, 1%1,Ser. No. 103,434 7 Claims. ((Jl. 173-17) This invention relates to apercussion drilling tool of the type adapted for operation with agaseous power fluid. More particularly, it concerns a motor whichdelivers percussive rblows to a drill bit as a gas is circulated throughthe motor.

My invention comprises a valve mechanism in the gasoperated motor whichcan be closed by raising the tool off the bottom of the hole, wherebygas flow through the motor will be reduced during interruptions indrilling operations.

In the rotary drilling of wells for the production of oil and gas, ithas been found that substantially greater drilling rates can be obtainedif percussive blows are applied to the drill bit as it rotates incontact with the rock formation. Motors have been designed for operationin the drill string adjacent the bit whereby energy in the circulatinggas stream can be used to power the motor and deliver percussive blowsto the bit. The gas which exhausts from the motor is discharged throughthe bit to aid in removing bit cuttings from the bottom of the well andto carry them to the surface.

Compressed gas in the drill pipe vented at the derrick floor when theswivel and kelly joint were removed in preparation for adding a joint ofdrill pipe. The gas blowing from the pipe produced considerabledifiiculties in adding joints of drill pipe. This problem wassubstantially overcome by placing a check valve in the drill stringbelow the kelly joint. Subsequent additions of drill pipe are made abovethe check valve, thereby avoiding the venting of gas from the entiredrill string. Each time the entire string of pipe is pulled to changedrill bits, the check valve is relocated above the joints of drill pipewhich were added following the previous round trip. In this manner thecheck valve is kept near the top of the drill string where it will bemost effective.

As drilling progressed to greater depths, a further problem developed.The high-pressure gas in the drill pipe between the motor at the lowerend and the check valve at the upper end continued to flow through themotor and up the well annulus while an additional joint of drill pipewas being added to the string. When the kelly joint and swivel werereconnected and gas flow resumed, considerable time was required for thecompressors to build up the pressure in the drill pipe to the desiredlevel for best operation of the percussion motor. On a well drilling ata depth of 8,00010,000 feet, as long as 15 minutes might be required torestore the gas pressure. During the time the operating pressure issubnormal, the motor runs at low speed, delivering light blows to thedrill bit, and less than normal quantities of gas are exhausted throughthe bit for removing bit cuttings.

I have invented a means for conserving the gas pressure in the drillstring during brief interruptions in the supply of power fluid, as whena joint of drill pipe is being added to the string. Upon the resumptionof drilling operations following such a stoppage, the pressure of thepower fluid delivered to the percussion motor is soon restored to thepeak operating level. The means by which I prevent the loss of gaspressure comprises a valve mechanism in the motor which closes orrestricts the passageway through the motor when the bit is lifted offthe bottom of the hole. The valve is arranged in such a way that it doesnot interfere with the motor during normal drilling operations.

It is therefore an object of my invention to reduce the loss of gaspressure from the drill pipe during interruptions in the supply ofhighpressure gas to the pipe.

Another object of this invention is to reduce the length of timerequired to repressure the drill pipe to the desired operating pressurefollowing a temporary stoppage of drilling operations.

These objects are accomplished using the apparatus in the mannerdescribed hereinafter in connection with the accompanying drawings.

FIGURE 1 is a view in cross-section of a percussion drilling motorhaving a valve adapted to close the fluid passageway through the motorwhen the bit is raised off bottom. In this view the valve is open andthe motor is operative.

FIGURE 2 is another view of the apparatus shown in FIGURE 1 with the bitlifted off bottom and the fluid passageway closed.

FIGURE 3 shows a cross-sectional view of a percussion motor having adevice for separating liquids carried in the air stream and bypassingthem through the motor or for bypassing extra gas through the motornecessary for hole cleaning but not needed for operating the motoreffectively. The valve member, inoperative in this figure, is located onthe bypass tube.

FIGURE 4 shows the apparatus of FIGURE 3 with the valve closing the gaspassageway through the percussion motor.

Referring now to FIGURE 1, the percussion motor 14 has a housing 11 withan anvil 12 in the lower end of the housing. A splined connection 13transmits rotary motion from the housing to the anvil as the anvil moveslongitudinally within the housing. The distance which the anvil can movewithin the housing is limited by the width of groove 15 in the anvil.Retainer balls 16 in the semicircular groove 17 in the housing 11 engagethe upper and lower ends of the wide groove 15, thereby limiting theextent of movement of the anvil within the housing. The halls areretained in the semicircular groove by set screw 18. A drill bit 19 isconnected to the lower end of the anvil 12. A hammer 21 is arranged forreciprocation inside housing 11 with the striking face 22 of the hammerdelivering percussive blows to the upper face 23 of the anvil.Passageway 24 equalizes the gas pressure inside the annular chamber 23with the motor exhaust in axial passageway 26 as the hammerreciprocates, varying the volume of chamber 25. Gas port 28 conducts thegas from the chamber 29 to a space within the housing between thestriking face 22 of t re hammer and the upper face 23 of the anvil.Inlet port 31 admits the gas to the chamber 29 from the drill pipe 32.An upper finger valve 34-, supported by radial ribs 35 in ring 36, isadapted to close inlet port 31 at the upper position of the hammer. Anadapter 33 holds the ring 36 in the upper end of the housing 11 andprovides a connection for the drill pipe 32. Valve member 38, separatedfrom the upper finger valve 34 by the reduced-diarneter section 37, ispositioned whereby it remains within the chamber 29 and does notinterfere with the operation of the motor while the splined connectionis retracted, as shown in FIGURE 1. On the other hand, valve member 38closes inlet port 31 when the bit 19 is raised off bottom, permittingthe extension of the splined connection as shown in FIGURE 2. In thisposition, the flow of gas through the motor is substantially terminated,thereby reducing the loss of gas pressure in the drill pipe. A cavity 39in valve member 38 is provided to enable the frequency of the hammer tobe adjusted. The volume of the cavity may be altered, e.g., either byfilling the cavity with a solid material or by placing a cover over thecavity, to adjust the gas capacity of chamber 29.

The percussion motor shown in FIGURES 3 and 4 L2 combines the valvemeans for retaining pressure in the drill pipe with a separator fordense materials carried in the gas stream. Curved vanes 41 between hub42 and ring 43 impart a circular motion to the gas stream flowing to themotor. Liquids separated from the gas in chamber 47 collect in thecircumferential trough 44 and the gas passes through openings 46 betweenthe radial troughs 45 connecting the circumferential trough with thebypass tube 48. The valve member 38 is attached to the bypass tube 48.If desired, the valve member may be hollow, as shown, to reduce itsmass. The length of valve member 38 may be chosen to produce the desiredgas volume in chamber 29.

It is preferable that the bypass tube be long enough so that it will notbe withdrawn from the lower opening 49 in the hammer, even when thesplined connection is extended, as shown in FIGURE 4.

With the splined connection '13 retracted as in FIG- URE 1, thepercussion motor 14 operates by the flow of gas through inlet port 31,chamber 29 and gas port 28. The hammer is lifted until upper fingervalve 34 closes inlet port 31. Momentum and expansion of the gas inchamber 29 continues to lift the hammer until the lower finger valve 27is withdrawn from axial passageway 26, permitting the gas in chamber29', and that between the hammer and anvil, to exhaust throughpassageway 26 and drill bit 19. Upon the decay of hammer momentum andthe reduction of pressure below the hammer, the pressure above thehammer is able to reverse the direction of travel and start the hammerdownward. First, the lower finger valve closes, then the gas trappedbetween the hammer and anvil flows through port 28, causing a slightincrease in the pressure in chamber 29. Upper finger valve 34subsequently clears inlet port 31, allowing high-pressure gas to flowinto chamber 29. S-ufficient momentum has been developed in the hammerthat it continues to move until it strikes the anvil, producing apercussive blow which is transmitted to the bit 19.

It will be noted that valve member 38 remained wholly within chamber 29during the above-described cycle of operation and in no way affectedvalve action. The volume of chamber 29 effects the frequency of thehammer, in that the pressure between the hammer and anvil must beequalized with that in the chamber via port 28. Therefore, the length oftime required to change the pressure below the hammer is increased inrelation to the volume of chamber 29. The volume may also be decreasedby using a hammer having thicker walls or by using a shorter hammer. Thethick-walled hammer is not desirable because the increased weight of thehammer decreases the blow frequency and usually requires redesign ofother motor components. The shorter hammer is also undesirable for thereason that it is less stable and tends to wobble within the housing,and may be less efficient in transferring kinetic energy to the bit. Apreferred method of reducing the volume of chamber 29 is to fill orotherwise close. cavity 39 in valve member 38.

When it becomes necessary to add a joint of drill pipe to the drillstring, the string is raised until the kelly joint is above the rotarytable. This raises the bit off bottom and enables the weight of the bitand anvil to extend the splined connection 13 as shown in FIGURE 2.Retainer.

balls 16 engage the upper end of wide groove 15. This lowers the hammerto a position where valve member 38 closes inlet port 31 with strikingface 22 of the hammer resting on upper face 23 of the anvil. In thisposition, there is not suflicient gas flow into chamber 29 to developthe momentum necessary to lift the hammer and open the lower fingervalve. Therefore, the flow of gas through the motor is substantiallystopped while the joint of drill pipe is being added to the drillstring. There may be a small flow of gas through the motor owing toleakage at the valves. in gas-operated motors of this type it is usuallydesirable to position the finger valves whereby both are closed throughabout half of the hammer upstroke and downstroke. In order that thehammer will not reciprocate when the splined connection is extended, thewide groove 15 should enable longitudinal displacement through adistance at least as great as the length of the lower finger valve. Thisarrangement will not permit the hammer to be lifted high enough to closethe top finger valve.

After the surface connections have been completed and the pipe islowered in the well, the bit may engage cuttings which have settled inthe well while gas circulation was stopped, or at least the circulationwas at a reduced rate. The splined connection will retract, permittinginlet port 31 to clear valve member 38. Hammer reciprocation can thenstart, providing gas circulation to carry the settled cuttings from thebottom of the hole. Also, there will be substantially no delay inreaching stabilized drilling operations because the gas pressure in thedrill pipe could not bleed down while the surface connections were beingmade.

In some instances it is desirable to inject small quantities of a liquidalong with the gas used to operate the drill. Ms is frequently nemssarywhen the well has penetrated water-producing zones. An oil, a foamingagent, or other material must he used to promote the removal of wet bitcuttings from the well. Substantial quantities of these materials do notpass through the percussion motor easily because they are substantiallynoncompressible. A separator and bypass arrangement, such as that shownin FIGURES 3 and 4, can be used to transport the noncompressible fluidsthrough the motor. The percussion motor is substantially equivalent tothat shown in FIGURES l and 2. The high-pressure gas containingentrained droplets fiows down the drill pipe and through adapter 33.Curved vanes 41 'between hub 42 and ring 4.3 impart a spiral motion tothe gas and droplets. The centrifugal force throws the droplets againstthe wall of separation chamber 47 where they collect and run down thewall into circumferential trough 44. The liquid drains through radialtroughs 45 into bypass tube 48 which conducts it through the motor toaxial passage 26. Gas in separation chamber 47 flows through openings 46between radial troughs 45, thence to the motor. Valve member 38 isattached to the bypass tube at a distance below upper finger valve 34,whereby it will close inlet port 31 when the splined connection 13 isextended as shown in FIG- URE 4. The outside diameter of member 38 issubstantially equal to the inside diameter of port 31. The volume of thechamber 29 may be adjusted by changing the volume occupied by valvemember 33. The diameter of that portion which enters port 31 cannot bealtered, therefore changes in the length or diameter must be restrictedto the lower end of valve member 38 where it does not engage the hammeror the inlet port.

The bypass tube should be long enough so that it is not withdrawn fromlower opening 49 in the hammer. Vibrations in the tube could move thetube out of axial alignment, causing it to strike the lower wall ofchamber 29 and damage the tool. The lower portion of opening 49 throughthe finger valve is bell-shaped to avoid interference of the gas flowthrough passageway 24- by the lower end of the bypass. It will beapparent that the bypass tube will continue to pass gas through themotor, even though valve member 33 has closed inlet port 31. The flowcapacity of the bypass tube is ordinarily quite small in relation tothat of the motor; therefore, the loss of pressure in the drill pipewill be considerably less than it is when the flow through the motor isnot stopped. In some instances it may be desirable to have a small flowof gas through the bit during short interruptions in drilling to hinderthe settling of cuttings in the annulus. The bypass tube would servethis purpose. A continuous flow of gas through the motor shown in FIGURE1 could be provided by an axial passageway, not shown, through upperfinger valve 34 and valve member 38, and a passageway from chamber 29through lower finger valve 27 to axial passageway 26.

From the above, it can be seen that I have provided a means forpreventing a substantial loss of gas pressure from the drill string whenthere has been an interruption in the injection of high-pressure gas atthe surface. This improvement is of particular value in that it reducesthe time required for the compressors to restore the desired operatingpressure level. it will be apparent that the valve member 33 should bepositioned in hammer chamber 29, whereby it does not interfere with theflow of gas through port 31 during vthe operation of the motor and at aposition whereby it closes port 31 when the splined connection isextended its maxirnum distance.

I claim:

1. A gas-operated percussion drilling tool comprising a hammer and ananvil, means for connecting a drill 'bit to said anvil, a housing forsaid hammer and anvil, an extensible splined connection between saidhousing and said anvil, an operating gas passageway through said hammerand anvil, a first inlet valve means and an outlet valve means in saidoperating gas passageway adapted to open and close said passagewayalternately as said ha mer reciprocates when said splined connection iscontracted, and a second inlet valve means adapted to close said gaspassageway when said splined connection is longitudinally extended andsad outlet valve means is closed.

2. A gas-operated percussion drilliri tool comprising a housing, ananvil in said housing, a splined connection between said housing aridsaid anvil, said connection being adapted for longitudinal movementbetween contracted and extended positions, a hammer in said housing,said hammer arranged for reciprocation in said housing above said anvilthereby producing a variable-volume chamber between said hammer andanvil, a metering chamber in said hammer, a gas passageway between saidmetering chamber and said variable-volume chamber, an axial gaspassageway through said anvil, a lower finger valve between said hammerand said axial gas passageway, a gas inlet in said metering chamber, afirst upper finger valve arranged to open and close said gas inlet assaid hammer reciprocates with said splined connection in its contractedposition, a second upper finger valve arranged to close said gas inletwhen said lower finger valve is closed at the extended position of saidsplined connection, thereby rendering said hammer inoperative.

3. A rotary-percussion drilling tool comprising a tubular housing, ahammer adapted for reciprocation in said housing, an anvil below saidhammer in said housing, a splined connection between said housing andanvil, means for limited longitudinal movement of said anvil in saidhousing, a metering chamber in said hammer, a gas inlet in said meteringchamber, an upper finger valve in said housing adapted to open and closesaid gas inlet as said hammer reciprocates in said housing, a volumereducer in said metering chamber depending from said upper finger valve,said volume reducer adapted to close said gas inlet when said splinedconnection is longitudinally extended.

4. In a gas-operated percussion drilling tool wherein a hammerreciprocates in a housing as gas flows therethrough under control of artupper and a lower gas valve and delivers percussive blows to an anvilrigidly afiixed to a drill bit, said reciprocation being produced by theflow of gas through said tool with alternate opening and closing of saidupper and lower gas valves, said anvil being adapted for limitedlongitudinal movement in said housing, the improvement comprising valvemeans adapted to block the flow of gas through said hammer when saidanvil is extended longitudinally and said lower gas valve is closed.

5. A gas-operated percussion drilling tool comprising a housing, ananvil in the lower end of said housing, a gas inlet at the upper end ofsaid housing, means for connecting a drill pipe to the upper end of saidhousing, a hammer arranged for reciprocation in said housing above saidanvil, a liquid extractor including collector means in said gas inlet, abypass tube axially disposed in said housing and extending, through saidhammer, means for conducting liquid from said collector to said bypasstube, a gas passageway through said hammer, said gas passagewayincluding inlet and outlet ports with a metering chamber between saidports, upper and lower finger valves adapted to open and close saidinlet and outlet ports in alternate sequence, a splined connectionbetween said housing and said anvil, an annular groove bet-ween saidanvil and said housing, a retainer means in said groove adapted to limitthe longitudinal movement of said anvil in said housing to a distanceequal to the width of said groove, the minimum width of said annulargroove being equal to the length of said lower finger valve, 21 valvemember on said bypass tube, said valve member being positioned wherebyit closes said inlet port when said lower finger valve is closed withsaid splined connection extended.

6. A gas-operated percussion drilling tool comprising a housing, ananvil in said housing, said anvil being arranged for longitudinalmovement between upper and lower positions in said housing, a hammeradapted for reciprocation in said housing above said anvil, a gaspassage through said hammer and anvil, said passage having a gas inletat the top of said hammer and a gas outlet in said anvil, a first inletvalve member and an outlet valve member arranged for alternate openingand closing of said gas inlet and gas outlet when said hammerreciprocates with said anvil in said upper position, a second inletvalve member positioned to close said gas inlet when said anvil is insaid lower position and said outlet valve member closes said gas outlet,and means to attach a bit to said anvil.

7. A gas-operated percussion drilling tool including a housing, an anvilin said housing, a splined connection betwwn said anvil and said housingadapted for longitudinal movement of said anvil between upper and lowerpositions in said housing, a hammer in said housing adapted forreciprocation above said anvil, a gas passage through said hammer andanvil, said gas passage including an inlet at the top of said hammer andan outlet in said anvil, a first upper valve member attached to saidhousing and arranged to open and close said gas passage inlet, a lowervalve member on the bottom of said hammer adapted to close said gaspassage outlet, the opening and closing of said gas passage inletalternating with that of said outlet as said hammer reciprocates withsaid anvil in said upper position, a second upper valve member attachedto said housing and arranged to close said gas passage inlet when saidanvil is at its lower position in said housing and said outlet isclosed.

References Eited in the file of this patent UNITED STATES PATENTS

1. A GAS-OPERATED PERCUSSION DRILLING TOOL COMPRISING A HAMMER AND ANANVIL, MEANS FOR CONNECTING A DRILL BIT TO SAID ANVIL, A HOUSING FORSAID HAMMER AND ANVIL, AN EXTENSIBLE SPLINED CONNECTION BETWEEN SAIDHOUSING AND SAID ANVIL, AN OPERATING GAS PASSAGEWAY THROUGH SAID HAMMERAND ANVIL, A FIRST INLET VALVE MEANS AND AN OUTLET VALVE MEANS IN SAIDOPERATING GAS PASSAGEWAY ADAPTED TO OPEN AND CLOSE SAID PASSAGEWAYALTERNATELY AS SAID HAMMER RECIPROCATES WHEN SAID SPLINED CONNECTION ISCONTRACTED, AND A SECOND INLET VALVE MEANS ADAPTED TO CLOSE SAID GASPASSAGEWAY WHEN SAID SPLINED CONNECTION IS LONGITUDINALLY EXTENDED ANDSAID OUTLET VALVE MEANS IS CLOSED.